摘要:

The pressure distribution due to a concentrated load on a semi‐infinite elastic body is given by the well‐known Boussinesq solution for either the two‐dimensional or three‐dimensional case. We here investigate the effect on such a pressure distribution, taken at the depthh,of the presence at that depth of a slippery rigid bed (case (b)); of a perfectly rough rigid bed (case (c)); and of a perfectly flexible but inextensible thin layer embedded in the material (case (d)). Both pressure distributions in the two and three‐dimensional problems are calculated for each case, Fig. 5 and Fig. 6. Several authors have already investigated case (b) and case (c) in two dimensions (2), (3). Their results are in perfect accordance with ours. The author is indebted to Dr. A. Casagrande for suggesting this investigation as a contribution to the field of soil mechanics.

ISSN:0021-8979    

DOI:10.1063/1.1745279

出版商:AIP    

年代:1935

数据来源: AIP

摘要:

The effect of heat treatment and of particle orientation on the magnetic properties of granular pyrrhotite are discussed and illustrated by curves and data. Heat treatment which causes little or no chemical change alters pyrrhotite so that increased induction and remanence and decreased coercive force result. Particles aligned in a filed parallel to that used in their magnetic measurement showed greater induction and remanence but less coercive force than randomly oriented material, while cross‐oriented particles showed the lowest induction and remanence but the greatest coercive force.

ISSN:0021-8979    

DOI:10.1063/1.1745280

出版商:AIP    

年代:1935

数据来源: AIP

摘要:

Studies were made of the unequal potential distribution commonly observed in insulating liquids under continuous potential difference. The potential distribution between parallel plates is measured in two insulating oils for over‐all voltages between 500 and 1500 volts, and at temperatures between 20 and 60°C. This distribution is produced by an accumulation of space charge near the electrodes which accumulation, however, extends measurably into the volume of the liquid. The amount of space charge as computed from the potential distribution increases with increase of applied voltage and decreases with increase in temperature. On reversal of the applied voltage, the initial over‐all conductivity is of approximately the same value as that preceding reversal. The initial current on reversal may remain constant over an appreciable interval, say from 1 to 4 sec. Following the initial constant value, the reverse current rises sharply to a maximum from 2 to 6 times the initial constant value, and at first rapidly and then slowly decreases to the same long‐time values as that of the preceding opposite potential. In this condition, a reversal of the foregoing pattern of potential distribution takes place.It is suggested that two types of ion are involved in the space charge, one of high mobility, and the other of low mobility, due to the accumulation about it of an aggregate of neutral molecules. Oscillographic studies of the variation of current on reversal offer means for approximate computations of the mobility of the ions involved. The mobility of the ions in a given liquid may take a wide range of values. As between different oils and for the same oil at different temperatures, mobilities vary inversely as the viscosity. In a low viscosity insulating oil a high value of 10−4cm/sec./volt/cm has been observed at 22°C.

ISSN:0021-8979    

DOI:10.1063/1.1745281

出版商:AIP    

年代:1935

数据来源: AIP

摘要:

Dynamical similarity laws of the high pressure mercury vapor discharge have been set up. These laws are based on principles which determine characteristics of a high pressure discharge in thermal equilibrium. Characteristics of discharges can be determined by measurements on models if the model contains the same mass of mercury gas per cm and is supplied with the same wattage per cm of length of tube as the main construction. The temperatures of the walls of discharge tube should be the same. In formulating the above requirements self‐absorption has been neglected. Experimental tests have shown the validity of the similarity theorems.

ISSN:0021-8979    

DOI:10.1063/1.1745282

出版商:AIP    

年代:1935

数据来源: AIP

摘要:

A method is described for the construction of electrical models with which to solve problems of the flow of liquids through porous media under the action of gravity. With these models the shape of the free surface and the extent of the surface of seepage are determined simultaneously with the potential distribution within the flow system. Four examples are given of the application of the method to the problem of the seepage of water through dams. In two cases the faces of the dams were assumed to be sloping, and in the others they were taken as vertical, the free surface and velocity distributions at the faces of one of the latter cases checking closely with those derived from an analytical solution of the problem. The method of applying these models to the study of more complex gravity flow systems is briefly indicated.

ISSN:0021-8979    

DOI:10.1063/1.1745283

出版商:AIP    

年代:1935

数据来源: AIP

摘要:

The method of hodographs, recently developed by Hamel for the analysis of ground‐water flow systems containing free surfaces, is applied numerically to six cases of the seepage of water through dams in which the ratio of the inflow fluid head to the width of the dam at the base varied from 2.04 to 1.08. In one case the velocity distribution was computed both along the inflow and outflow faces, as well as along the base of the dam. The pressure and velocity distributions along the bases and the velocity distribution along the inflow faces were found for 5 other cases, in 4 of which the outflow fluid head was zero. The heights of the surfaces of seepage and the total fluxes were calculated for all six cases. These calculations show that the Dupuit‐Forchheimer theory of the free surface and velocity distributions in gravity flow systems is definitely wrong, and that the extension of the empirical results of Wyckoff, Botset and Muskat, obtained with radial gravity flow systems, to linear systems is unjustified. The fluxes, however, given by this extension or the Dupuit‐Forchheimer theory turn out to be in close agreement with those calculated by the exact theory. The evaluation of the fundamental integral over the argument of the modular elliptic function involved in the calculations is extended beyond the range given by Hamel and Gunther so as to include all real values of the modular elliptic function.

ISSN:0021-8979    

DOI:10.1063/1.1745284

出版商:AIP    

年代:1935

数据来源: AIP

摘要:

With a new type of especially stable electrolytic capacitor, the dielectric properties of anodic layers are measured. The investigation shows that variations of the dielectric properties may be divided into two classes: lagging and nonlagging variations. Lagging variations, which include variations of the capacity and power factor with the operaing voltages, are especially characteristic of anodic layers. They arise from the fact that the structure (organization) of layers adjusts itself with changes of the operating conditions to a new dynamic equilibrium, within a short transition period. On the other hand, in regard to variations of the capacity and power factor with frequency, which are nonlagging variations, anodic layers are similar to other composite dielectrics. An oscillographic study of harmonics is made which verifies the lagging nature of the changes of capacity with the operating voltages (a.c. and d.c.) and demonstrates for the first time the existence of a nonlagging variation of the a.c. conductivity with voltage.

ISSN:0021-8979    

DOI:10.1063/1.1745285

出版商:AIP    

年代:1935

数据来源: AIP